1. Field of the Invention
The present invention relates to a telecommunications system having particular, but not exclusive, application to a multiple primary station mobile radio system capable of providing multiple-participant communications with hand-over between primary stations of a call-in-progress.
2. Description of the Related Art
A mobile radio system can use handover to ensure continuity of calls in progress as mobile secondary stations move between the coverage areas of different fixed primary stations. Trunked mobile radio systems, for example MPT 1327 published by the DTI London, have been known for some time that permit communication between more than two participants in a call. Such calls are typically referred to as group calls. When a number of primary stations and secondary stations are involved in group calls the signalling requirements as primary stations hand-over calls involving mobile secondary stations can, using known techniques, become high enough to degrade system performance or require excessive allocation of frequency resource to control signalling.